PMDG 737 falling out of the sky!

[chrishayes001 0]

Hi all

 

I got PMDG 737 a week or so ago. I'm very excited. It's magnificent. But (always a but, isn't there!)  I have gone through the entire 1st Tutorial Flight set up five times, I've copied every setting into the FMC and every instruction meticulously just as the Tutorial states on the page. But something is wrong

 

Everything is fine to start with climbing upwards with MCP SPD LNAV an ALT ACO showing. Until the plane suddenly starts to lose height and the alarms start ringing! I have been puzzling over this searching for something I might have entered incorrectly until I noticed that final LEGS page on the 1^st Tutorial instructions (dated 20FEB12) are different from my final LEGS page although I am inputting the same data.

 

The final LEGS page in the Tutorial looks like this:

0.79 ° TRK 2.5NM

(702) 163/ 702

0.79 ° TRK 0.5NM

(INTC) 219/ 2711

0.92° 13.5NM

TUNBY 250/5000

0.92° 8.0NM

etc

 

The LEGS page I get is:(differences in italics)

0.79 ° TRK 2.4NM

(702) 163/ 702

0.79 ° TRK 3.7NM

(INTC) 219/ 2711

0.92° 13.6NM

TUNBY 250/5000

0.92° 8.0NM

 

I don't understand how the distances can be different but could this be why the plane falls out of the sky! And if so how can I remedy it?

 

Any help very gratefully accepted.

 

Thanks

 

Chris

[SierraHotel 976]

Hi Chris, what date is the AIRAC? Do you have the latest? That can cause discrepancies, especially if one add-on is using one and the aircraft an earlier or later one.  Although that shouldn't cause the aircraft to lose speed/altitude. Did you check that VNAV was live and connected?

[Jim Young 2,356]

 

 

Everything is fine to start with climbing upwards with MCP SPD LNAV

 

Well, that's the problem.  SPD is showing.  You need to increase the speed setting to about 150-160 so that your aircraft will be going fast enough until you engage the AP.  I usually set mine to 180 until the AP/LNAV/VNAV takes over.  In the FMC, on the TakeOff page, you want to make sure you have V1 and V2 set too.

 

Best regards,

Jim

[chrishayes001 0]

Hi, SierraHotel

 

Thanks for your reply.

 

I downloaded the programme a week ago. It has AIRAC-1108 ACTIVE: JUL28AUG24/11. The 1st Tutorial I am following that came with the download uses a different AIRAC-1100 but, confusingly, it has the same ACTIVE: JUL28AUG24/11. 

 

I presume this accounts for the different distances NMs I experienced from the same inputs as above - although I don't understand how different AIRAC numbers can cover the same time period in the real world.

 

Is the AIRAC info hardwired in the PMDG programme or can it be updated?

 

I will start again and re-programme the FMC etc. as per the Tutorial once more - good practice - and I'll see what happens to the flight this time. As you say it seems odd to lose that it would cause losing speed/altitude.

 

Glad for your advice. Thanks again.

 

Chris

[Adam T Lutley 12]

Sounds like the aircraft is stalling. The MCP speed mode tells you that the autothrottle is setting your speed based upon what you have set on the mode control panel, not what you have programmed in the FMC. I generally don't engage VNav or LNav until at least 2500-3000ft AGL and not until after I've cleaned the aircraft up after takeoff. Your climb out speed should not be less than around 180 KTS in this configuration ( flaps and slats retracted).

[SierraHotel 976]

Hi, SierraHotel

 

Thanks for your reply.

 

I downloaded the programme a week ago. It has AIRAC-1108 ACTIVE: JUL28AUG24/11. The 1st Tutorial I am following that came with the download uses a different AIRAC-1100 but, confusingly, it has the same ACTIVE: JUL28AUG24/11. 

 

I presume this accounts for the different distances NMs I experienced from the same inputs as above - although I don't understand how different AIRAC numbers can cover the same time period in the real world.

 

Is the AIRAC info hardwired in the PMDG programme or can it be updated?

 

I will start again and re-programme the FMC etc. as per the Tutorial once more - good practice - and I'll see what happens to the flight this time. As you say it seems odd to lose that it would cause losing speed/altitude.

 

Glad for your advice. Thanks again.

 

Chris

The latest AIRAC can be purchased at Navigraph http://www.navigraph.com/ I update mine bi-monthly, but it's up to you. A new cycle is released once a month, and that cycle will cover you for all addons eg NGX, ProATC, Aivlasoft EFB etc. Re the VNAV, when you have programmed the FMC if the VNAV button lights up, you know all is well (Same for LNAV) I always make a point of checking both VNAV and LNAV before proceeding with start up. Re switching to VNAV/LNAV, I think the FCOM says after you have passed 1200'

[chrishayes001 0]

Thanks, everyone, for your help. 

 

Eventually I got to the bottom of what was happening. And I am much relieved.  I can't believe I was being so stupid. I could see that VNAV or LNAV and sometimes CMD A or all three were disengaging for some reason. But I couldn't understand why... then it suddenly hit me. Literally!

 

I knew not to move the joystick while in a/p but I hadn't appreciated that the lightest touch to steady a wildly flapping stick was so catastrophic. I use a Logitech Force3DPro and it whacks back and forth with a vengeance.Trying to gently calm it was the culprit of all my troubles! It faithfully follows all the twists and turns of the screen yoke. Which is realistic. But do real plane's have a kind of docking or dampering device? It must be lethal in the cockpit otherwise!

 

I always found this stick satisfactory before moving up to PMDG 737 and I maybe be able to alter the settings to make it less wild. But perhaps I need to get something different. I'd be very grateful for any suggestions.

 

Thanks again.

 

Chris

[Don t moderate me this way 882]

Try to increase null zones. IIRC, the NGX has an option for 'less realistic' A/P engagement which should help with your dis-engagement issue, as well.

[chrishayes001 0]

Thanks Olly4740.

 

I already had Ailerons, Elevator and Rudder Null Zones as high as they go before I even started with this plane. I found that the Force3D stick is too lively with anything - although you get a nice wobble and a grumble when it goes over the gravel. I have just discovered, though, that I can taxi and take off with the stick as it is and then immediately before engaging the a/p I pull out its power supply and it behaves like a baby. The rest of the controls on the stick work fine and I even found that if I gave the stick a great tug the a/p disengages just as it is meant to do!

 

Mind you I haven't landed yet! 

 

I can't help thinking there is a better stick for this plane out there though?

[bennyboy75 85]

You really could do with a yoke to fly the NGX realistically. Saitek and CH both make decent ones which are widely available.

 

Also might be worth looking at FSUIPC to map your control axis to. FSX's own axis configurator is often the cause of many problems.

 

You can depart with LNAV and VNAV engaged in the NGX or use TOGA and once you reach acceleration height (the point at which N1 illuminates on the MCP), select HDG SEL, rotate the speed knob to the flaps up speed and then select VNAV when the flaps are up.